It is known that the sealing problem between a pump shaft and a pump body where the shaft leaves the body is generally imperfectly solved. Consequently, although slight leakages of inert liquids such as water can be tolerated, when said pump pumps a corrosive fluid such as an acid, possibly at high temperature, there must be no leakage at all.
Devices usually used to provide such sealing include packing boxes and rotating seals with mechanical packing, such arrangements being necessarily disposed between the pump shaft and the pump body.
Now, it is known that such devices wear more or less rapidly, especially when the pump conveys liquids which contain solid particles in suspension; therefore, sealing rapidly becomes incomplete. One remedy to such a drawback is to use a hydrodynamic discharge pump fixed on the shaft inside the pump body, in the neighbourhood of the output of said shaft. Such a turbine, which is generally an impeller wheel, produces a suction at the output of the shaft, thereby preventing the fluid from remaining permanently at the shaft output.
However, when the pump stops, sealing must be provided. This requires a packing box to be tightened by means of screws. Of course, the box must be loosened before the pump is subsequently restarted, since if this is not done, the packing box rapidly seizes, thereby putting the pump out of action.
The need to tighten and loosen the packing box by hand when the pump is stopped and started is a hindrance, especially in an industrial installation where a large number of pumps are generally used, since as previously mentioned, neglecting such operations can lead to putting a pump out of action and to shutting down an installation.
The present invention provides a means of performing such tightening and loosening operations automatically and reliably by using a simple and inexpensive device which is described hereinbelow.